I am glad this topic came up because I, too, need help deciding which kit to buy for my '69 GS400 that will be wearing 15-inch wheels. I only want to convert the fronts to disc right now. And my car is a NON-power car, so no booster. The questions I need help with are: 1. Are these kits intended to only be used with a booster, or will they work on a system that has a non-PB master cylinder? 2. If I can install disc brakes on the front while keeping it non-power, will I be able to stop the car? Or will it require so much pedal strength that only Lou Ferrigno would be strong enough? 3. Would going with 2-piston calipers lessen the leg strength required to stop the car? Thanks guys.